The scalability of any microbial fuel cell (MFC)-based system is of vital importance if it is to be utilized for potential field applications. In this study, an integrated MFC–aerobic bioreactor system was investigated for its scalability with the purpose of treating a simulated dye wastewater and industrial wastewaters originated from textile dyebaths and leather tanning. The influent containing real wastewater was fed into the reactor in continuous mode at ambient temperature. Three MFC units were integrated to act in unison as a single module for wastewater treatment and a continuously stirred aerobic bioreactor operating downstream to the MFC module was installed in order to ensure more complete degradation of colouring agents found in the wastewater. Total colour removal in the final effluent exceeded 90% in all experiments where both synthetic (AO-7 containing) and real wastewater were used as the influent feed. The chemical oxygen demand reduction also exceeded 80% in all experiments under the same conditions. The MFC modules connected in parallel configuration allowed obtaining higher current densities than that can be obtained from a single MFC unit. The maximum current density of the MFC stack reached 1150 mA m−2 when connected in a parallel configuration. The outcome of this work implies that suitably up-scaled MFC–aerobic integrated bioprocesses could be used for colour industry wastewater treatment under industrially relevant conditions with possible prospects of bioelectricity generation.